Turbulent natural-convection heat transfer on a vertical surface under stepwise heating with inversion of heat flux

Results are given of experimental investigations of air flow in the vicinity of a vertical plate under stepwise heating which leads to inversion of heat flux on the surface. It is suggested to generalize to this case the algebraic model of turbulent thermal diffusivity developed by us previously. The results of calculations of such flow are compared with experimental data, and special features of the structure of thermal layer are identified.     

Kinetic Monte Carlo simulations of plasma-surface reactions on heterogeneous surfaces

Reactions of atoms and molecules on chamber walls in contact with low temperature plasmas are important in various technological applications. Plasma-surface interactions are complex and relatively poorly understood. Experiments performed over the last decade by several groups prove that interactions of reactive species with relevant plasma-facing materials are characterized by distributions of adsorption energy and reactivity. In this paper, we develop a kinetic Monte Carlo (KMC) model that can effectively handle chemical kinetics on such heterogenous surfaces. Using this model, we analyse published adsorption-desorption kinetics of chlorine molecules and recombination of oxygen atoms on rotating substrates as a test case for the KMC model.     

Carbon Nanotubes on Polymeric Microcapsules: Free‐Standing Structures and Point‐Wise Laser Openings

Single‐wall carbon nanotubes modified by anionic polyelectrolyte molecules are embedded into the shells of microcapsules. Carbon nanotubes serve as rigid rods in a softer polymeric capsule, which forms a free‐standing shell upon treatment with glutaraldehyde and subsequent drying. The embedded carbon nanotubes exhibit a broad absorption in the UV–near‐infrared part of the spectrum, and that allows point‐wise activation and opening of the microcapsules by laser. Raman signal analysis shows changes of carbon‐nanotube‐specific lines after high‐power laser irradiation, which is characteristic of the formation of disordered carbonlike structures. These polyelectrolyte/carbon nanotube composite capsules represent a novel light‐addressable type of microcontainers.     

Correlation of acoustic,physicochemical, and mechanical properties of coatings obtained using electron-beam welding deposition of chromium carbide on low-carbon steel

Multifunctional coatings have been developed using the method of nonvacuum electron-beam welding deposition of chromium carbide powder on low-carbon steel. The correlation dependences of the ultrasonic velocity, the thickness of coatings, the content of chromium in the coatings, and the loss of mass under exposure to corrosive media on the mechanical properties are constructed using the bend tests. It was shown that the observed correlation relations are mainly determined by two factors, i.e., the presence of a substitute doping agent of chromium in a solid solution and the character of a dislocation structure, which forms inside of the grain.     

Calibration of pulse pressure sensors using the laser near-surface air breakdown

A method for calibrating pulse pressure sensors by a spherical shock wave, generated by the laser near-surface air breakdown, is proposed. The method is based on comparing the breakdown shock wave amplitude, measured by the calibrated sensor, and the calculated amplitude for identical breakdown conditions. The amplitude of the shock wave is calculated by the Sadowski formula with coefficients modified with reference to the laser blast.     

Basics of a new energy-saving technology for manufacturing clay tile

A process for fabricating clay tile by hydrostatic treatment and a device for its production are described. The suggested technology is distinguished from existing ones by an elevated and uniform density of the tile, which improves the quality of the product and makes it possible to decrease its thickness while retaining the requisite service parameters, and it makes the use of all drying equipment unnecessary and reduces the firing temperature. Implementation of the new technology makes it possible to widen the range of products and use lean low-plasticity clays.     

Estimating IC susceptibility to single-event latchup

The results are presented of a computer and physical simulation concerned with the estimation of CMOS-circuit susceptibility to single-event latchup. A laser-simulation procedure is proposed and tested in which only the most sensitive areas are irradiated. The estimates are found to agree with the measurements.     

Electronic properties of AlVO<Subscript>4</Subscript> for gas sensor applications

The binary oxide AlVO₄ is being proposed as a new gas sensor material. An X-ray investigation, IR spectrum analysis, resistivity and a calculation of the electronic structure of this compound have been carried out in order to determine its structural, absorptive and sensor properties. The fragment [Al₃V₃O₂₃]¹⁸⁻ is the chain chosen to study the electronic properties of AlVO₄ in the framework of the frontier orbital theory and the interaction between molecules has been described by the Molecular Electrostatic Potential (MEP). The vibration analysis and the simulated infrared spectrum (IR) were calculated for the unit [Al₃V₃O₂₃]¹⁸⁻ and a comparative analysis with the experimental spectrum of AlVO₄ is also presented.     

On the possibility of learning in reactive environments with arbitrary dependence

We address the problem of reinforcement learning in which observations may exhibit an arbitrary form of stochastic dependence on past observations and actions, i.e. environments more general than (PO)MDPs. The task for an agent is to attain the best possible asymptotic reward where the true generating environment is unknown, but belongs to a known countable family of environments. We find some sufficient conditions on the class of environments under which an agent exists which attains the best asymptotic reward for any environment in the class. We analyze how tight these conditions are, and how they relate to different probabilistic assumptions known in reinforcement learning and related fields, such as Markov Decision Processes and mixing conditions.